Hi!
I just happen to have exactly the same car.
And I also had similar problems.
First the car would lack power especially when cold and it would even die (sometimes when driving at 20-30 Mph)
I changed the spark plug cables and spark plugs and it got better for about a month. So I decided to replace the O. E. cables with NOLOGY cables ( A fortune! ) and Silverstone spark plugs ( Go see: Nology.com ) And it worked!...
A second problem I had, months later, was no power at all. The engine would start but if it hadn't been for the slope to the mechanic's, I would have never made it.
He took apart all the air intake system ( The grey, pipe-like,metallic things on top of the engine ) and cleaned it thoroughly; and the injectors as well. 100 000 miles and that had never been done!
Since then the car the car has worked beautifully!
Michel Malavialle, July 2005